Field of the Invention
This invention relates to selectable-ratio transmissions and to simplified determination, during assembly, of the parts to be used therein. In particular, it relates to a selectable-ratio transmission using color coding of certain gears that determine the overall gear ratio to simplify assembly instructions and of other components to identify, after assembly of the enclosed transmission, the gears used in it.
The transmission of this invention is particularly useful in electrically powered toy vehicles of a size large enough to be ridden by small children up to the age of about ten years or so. The power is typically obtained from one or more rechargeable batteries carried on the vehicle and connected by child-actuated switches and controls to a drive motor, or preferably two drive motors, each connected by a transmission to one or more drive wheels of the vehicle. By using transmissions that have high speed-reduction ratios (typically more than 80:1), the speed of the vehicle may be kept acceptably low and the motor torque may be multiplied sufficiently to permit the vehicle to be operated by small motors on surfaces that are less than perfectly smooth.
The lower the ratio, the higher the speed. However, a lower gear ratio results in lower torque multiplication, and the vehicle may not operate on grass, for example, or it may not be capable of going up even a gentle incline. It may also drain charge from the battery power pack too quickly. Too high a ratio may save the battery and provide enough torque to traverse any terrain, but may cause the vehicle to be so slow that children will not enjoy it. Variations in driven wheel diameter also give rise to the need for different speed reduction ratios.
As a result, different gear ratios may be required for different types of toy vehicles, but it is desirable to use virtually the same transmissions in all of them. That can be done if the overall gear ratio can easily be selected from two or more specific values during assembly of the transmissions. In order to simplify instructions to workers selecting and assembling the parts, the transmissions must have some simple means of indicating which gears to use for a certain ratio. It is also desirable that most of the parts in every transmission be the same and that only a small number be changed to change the gear ratio.
The transmissions are provided with housings that are essentially closed to retain lubricant and to exclude dirt. Thus, the gears that determine the transmission ratio of each transmission are not visible after the transmission has been completely assembled, but it is still necessary to identify transmissions in inventory as having one gear ratio rather than another so that workers assembling a toy vehicle can select the proper transmission out of inventory.